Synthesis and single-crystal characterization of novel 2-ferrocenyl-4H-pyrazolo[5,1-c][1,4]oxazin-4-one derivatives

A series of novel 2-ferrocenyl-6-substituted-4H-pyrazolo[5,1-c][1,4]oxazin-4-one derivatives were synthesized by the intra-esterification reaction of ethyl 1-(2-aryl-2-oxoethyl)-3-ferrocenyl-1H-pyrazole-5-carboxylate in the presence of magnesium bromide and diisopropylethylamine in one-pot procedure. The structures of compounds were characterized by 1H NMR, 13C NMR, IR, HRMS and X-ray diffraction analysis.